Which of the following are true, regarding production costs:

Average fixed costs increase with each additional unit of production.

At a given output level, if average total costs are decreasing, it must be the case that producing the next unit of output will have a marginal cost that is greater than the average total cost.

At a given output level, if average total costs are increasing, it must be the case that marginal cost is greater than average fixed costs.

None of the above are true.